topic Re: Roof rafters and ceiling joists in Modeling

Roof rafters and ceiling joists

Anonymous — Tue, 23 May 2023 12:56:16 GMT

I'm not sure if this belongs in here or in the Construction Documentation section, but it made more sense here to me.

I'm trying to correctly model a residential light wood framing wall section with a vaulted ceiling and running into a couple of issues. I'm still very new to ArchiCAD so hopefully there are some easy fixes for these issues, but I searched the forums for everything that I thought might be relevant and didn't find anything to address these specific issues.

Firstly, how can I show the roof rafter and ceiling joist intersection properly? In this situation, we have a "vaulted" ceiling that intersects the roof framing where the ceiling joists are offset from the rafters and framed into the roof rafters, so they would actually continue beyond the rafter line like shown, but how can I show the gypsum board in the section to stop where the rafters and joists intersect? Obviously they would not be putting gypsum board in the inaccessible attic space above the ceiling joists, so we need to show the gypsum board stop and wrap around the ceiling corner. The only way I can think of to accomplish this is either using fills to block out parts of the rafters and joists or creating two roof types, one with gypsum board on the bottom and one without in appropriate places.

Secondly, is the only way to show the rafter-wall intersection properly going to be by SEO'ing parts of the wall away? We need to show the stud framing and sheathing come up into the rafter as the bearing element, with the brick veneer stopping at the underside of the rafter tail, covered by the frieze board trim piece.

If anyone could shed some light onto this situation I would greatly appreciate it.

Re: Roof rafters and ceiling joists

Gerald Hoffman — Mon, 07 Jun 2010 15:26:17 GMT

First off I would model the ceiling gypsum board separatly with the roof tool rather than as part of a composite. It is then very simple to join them properly. I put these on a separate layer for Ceiling Finishes.

I am not sure what detail you wanted to have on the outside of the wall. Typically I would take the brick up to the underside of the frieze board. Is this what you were trying to do? If yes, you can create your wall with a Wall Profile ( lots of information on this on Archicad-Talk ). You could also add the required back framing for the frieze board into your wall profile.

Hope this helps, Cheers,

Re: Roof rafters and ceiling joists

Anonymous — Mon, 07 Jun 2010 16:41:39 GMT

Thanks Gerald.

I hadn't thought to create the ceiling finish separately from the roof structure since ArchiCAD has the composites built-in. That fixed the rafter-ceiling gypsum board intersection, but now the wall-rafter gypsum board intersection does not clean up properly, presumably because the rafter gyp. board is no longer part of a composite structure.

As for the wall, I'm using ArchiCAD Start Edition 2010, and my understanding is that its limited features include not having wall profile abilities. Maybe someone has another idea on how to get this to show correctly? If not I don't think it's too huge of a deal, but it would be nice to be able to get the wall section to show accurately without additional 2D drafting work.

Re: Roof rafters and ceiling joists

Gerald Hoffman — Mon, 07 Jun 2010 22:37:00 GMT

rbrainard wrote:
Thanks Gerald.

I hadn't thought to create the ceiling finish separately from the roof structure since ArchiCAD has the composites built-in. That fixed the rafter-ceiling gypsum board intersection, but now the wall-rafter gypsum board intersection does not clean up properly, presumably because the rafter gyp. board is no longer part of a composite structure.

As for the wall, I'm using ArchiCAD Start Edition 2010, and my understanding is that its limited features include not having wall profile abilities. Maybe someone has another idea on how to get this to show correctly? If not I don't think it's too huge of a deal, but it would be nice to be able to get the wall section to show accurately without additional 2D drafting work.

You will have the problem of the intersection at the wall. You could extend the ceiling gypsum into the wall to the depth of the wall gypsum and then subtract the wall gypsum with SEOs.

I didn't know what version you were using. It is helpful on the forum to put your version of software and hardware in your signature. (See many examples ) so people know how to respond. Before composite structures I used to model things like this all the time just using multiple walls. If they touch you can have some problems walls cleaning up in ways you don't want them to so you have to assign different wall priorities to the different types of walls. Also if you can leave a gap between your brick course and the framing wall which is what we do here anyway, you won't have that problem. Basically it sometimes helps to think about modeling the way you would have to build it.

Cheers,

Re: Roof rafters and ceiling joists

Anonymous — Tue, 08 Jun 2010 13:53:21 GMT

Many thanks. I don't know why I didn't think of SEOing the extra gypsum out myself, ever since I discovered and figured out how to use SEO it's been one of my best friends, since I don't have profiling abilities in Start Edition. I've also managed to "fudge" the wall portions enough by SEOing parts of the brick behind the frieze board out and drawing the additional details with lines and fills so that it is correct.

I am somewhat familiar with modeling software, since I use Revit (isn't that a bit of a shunned word here? ) in school, I'm just new to ArchiCAD since we just switched over from Architectural Desktop starting this summer.